Semiconductor devices having gate structures with skirt regions

ABSTRACT

Provided are a semiconductor device and a method for fabricating the same. The semiconductor device includes an active fin protruding upwardly from a substrate and extending in a first direction and a gate structure extending in a second direction intersecting to cross the active fin, where a first width of a lower portion of the gate structure that contacts the active fin is greater than a second width of the lower portion of the gate structure that is spaced apart from the active fin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/220,028 filed Dec. 14, 2018, which is a continuation of U.S.application Ser. No. 14/988,819 filed Jan. 6, 2016, which claimspriority under 35 U.S.C. § 119 to Korean Patent Application No.10-2015-0006772 filed Jan. 14, 2015 in the Korean Intellectual PropertyOffice and to U.S. Provisional Patent Application No. 62/104,539 filedJan. 16, 2015 in the United States Patent and Trademark Office, thecontent of each of which is incorporated herein by reference.

BACKGROUND

A multi-gate transistor has been proposed as a potential technique forincreasing the density of integrated circuit devices. A multi-gatetransistor has a fin-shaped or nanowire-shaped semiconductor body thatis formed on a substrate and a gate is then formed on a surface of thesemiconductor body. Since multi-gate transistors use three-dimensional(3D) channels, scaling of the multi-gate transistor is easily achieved.In addition, current controlling capability can be improved withoutincreasing a gate length of the multi-gate transistor. Further, a shortchannel effect (SCE), in which an electric potential of a channel regionis affected by a drain voltage, can be suppressed in multi-gatetransistors.

SUMMARY

The inventive concepts provide semiconductor devices having improvedoperating characteristics.

According to an aspect of the inventive concepts, there is provided asemiconductor device including an active fin protruding from a substrateand extending in a first direction, a gate structure extending in asecond direction that intersects the first direction, the gate structureon the active fin, and a field insulation layer on a bottom portion of along side of the active fin, the intersection of a top surface of thefield insulation layer and the active fin defining at least one linesegment, where the gate structure includes a skirt that extendsoutwardly in the first direction to cover a portion of the at least oneline segment while leaving another portion of the at least one linesegment exposed.

According to another aspect of the inventive concepts, there is provideda semiconductor device including first and second active fins protrudingupwardly from a substrate and extending in parallel to each other in afirst direction, and a first gate structure extending in a seconddirection that intersects the first direction, the first gate structureon the active fin and on the second active fin, wherein the first gatestructure includes a first skirt where a first side of the first gatestructure extends outwardly in the first direction to contact a firstside of the first active fin, a second skirt where a second side of thefirst gate structure extends outwardly in the first direction to contactthe first side of the first active fin, the second side of the firstgate structure being opposite the first side of the first gatestructure, a third skirt where the first side of the first gatestructure extends outwardly in the first direction to contact a firstside of the second active fin that faces the first side of the firstactive fin, and a fourth skirt where the second side of the first gatestructure extends outwardly in the first direction to contact the firstside of the second active fin.

According to still another aspect of the inventive concepts, there isprovided a semiconductor device including an active fin protruding froma substrate and extending in a first direction, a gate structureextending in a second direction that intersects the first direction, thegate structure crossing the active fin, and a dummy gate structureextending in the second direction to cross the active fin, the activefin having an end positioned under the dummy gate structure, wherein thedummy gate structure includes a first skirt where a first side of thedummy gate structure extends outwardly in the first direction to contacta side surface of the active fin.

According to a further aspect of the inventive concepts, there isprovided a semiconductor device including first and second active finsprotruding from a substrate and extending in parallel to each other in afirst direction, a first gate structure extending in a second directionthat intersects the first direction, the first gate structure on thefirst and second active fins, and a second gate structure extendingparallel to the first gate structure, the second gate structure on thefirst and second active fins, wherein the first gate structure includesa first region adjacent the first active fin and a second region that isspaced apart from the first and second active fins, the first regionhaving a greater width than the second region, and the second gatestructure includes a third region adjacent the first active fin and afourth region that is spaced apart from the first and second activefins, the third region having a greater width than the fourth region.

According to yet another aspect of the inventive concepts, there isprovided a semiconductor device including an active fin protruding froma substrate and extending in a first direction, a field insulation layeradjacent a long side of the active fin, a gate structure extending in asecond direction on the field insulation layer to intersect the activefin, and spacers on at least one side of the gate structure andextending in the second direction, wherein the gate structure includes afirst portion where the gate structure extends underneath the spacer anda second portion where the gate structure does not extend underneath thespacer.

According to yet another aspect of the inventive concepts, there isprovided a semiconductor device that includes a substrate, an active finprotruding upwardly from the substrate and extending in a firstdirection, and a gate structure that extends in a second direction tocross the active fin, wherein a first width of a lower portion of thegate structure that contacts the active fin is greater than a secondwidth of the lower portion of the gate structure that is spaced apartfrom the active fin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a layout view illustrating gate structures and active fins ofa semiconductor device according to an embodiment of the inventiveconcepts;

FIG. 2 is a perspective view illustrating one of the gate structures andone of the active fins of the semiconductor device of FIG. 1 ;

FIG. 3 is a cross-sectional view taken along the line A-A′ of FIG. 1 ;

FIG. 4A is a cross-sectional view taken along the line B-B′ of FIG. 1 ;

FIG. 4B is a cross-sectional view taken along the line B1-B1′ of FIG. 1, illustrating a region A1 of FIG. 1 ;

FIG. 4C is a cross-sectional view taken along the line B2-B2′ of FIG. 1, illustrating a region A2 of FIG. 1 ;

FIG. 5 is a layout view illustrating gate structures and active fins ofa semiconductor device according to another embodiment of the inventiveconcepts;

FIG. 6 is a cross-sectional view taken along the line C-C′ of FIG. 5 ;

FIG. 7 is a layout view illustrating a gate structure and active fins ofa semiconductor device according to still another embodiment of theinventive concepts;

FIG. 8 is a cross-sectional view taken along the line D-D′ of FIG. 7 ;

FIG. 9A is a layout view illustrating gate structures and active fins ofa semiconductor device according to still another embodiment of theinventive concepts;

FIG. 9B is a cross-sectional view taken along the line E-E′ of FIG. 9A;

FIG. 10 is a circuit view illustrating a semiconductor device accordingto still another embodiment of the inventive concepts;

FIG. 11 is a layout view of the semiconductor device of FIG. 10 ;

FIG. 12 is a block diagram of a System on Chip (SoC) system includingsemiconductor devices according to some embodiments of the inventiveconcepts;

FIG. 13 is a block diagram of an electronic system includingsemiconductor devices according to some embodiments of the inventiveconcepts;

FIGS. 14 to 16 illustrate exemplary semiconductor systems to whichsemiconductor devices according to some embodiments of the inventiveconcepts can be applied;

FIGS. 17 to 20 are diagrams illustrating a method for fabricatingsemiconductor devices according to some embodiments of the inventiveconcepts.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the inventive concepts will be described in detail withreference to the accompanying drawings. The inventive concepts, however,may be embodied in various forms, and should not be construed as beinglimited to the illustrated embodiments. Rather, these embodiments areprovided as examples so that this disclosure will be thorough andcomplete, and will fully convey the inventive concepts to those skilledin the art. Known processes, elements, and techniques may not bedescribed with respect to some of the embodiments of the inventiveconcepts. Unless otherwise noted, like reference numerals denote likeelements throughout the attached drawings and written description, andthus descriptions will not be repeated. In the drawings, the sizes andrelative sizes of layers and regions may be exaggerated for clarity.

It will be understood that, although the terms “first”, “second”,“third”, etc., may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section without departing from the teachings of the inventiveconcepts.

Spatially relative terms, such as “beneath”, “below”, “lower”, “under”,“above”, “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement or feature as illustrated in the figures. It will be understoodthat the spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” or“under” other elements or features would then be oriented “above” theother elements or features. Thus, the exemplary terms “below” and“under” can encompass both an orientation of above and below. The devicemay be otherwise oriented (rotated 90 degrees or at other orientations)and the spatially relative descriptors used herein interpretedaccordingly. In addition, it will also be understood that when a layeris referred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the inventiveconcepts. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, operations, elements, components, and/or groups thereof.As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items. Also, the term “exemplary”is intended to refer to an example or illustration.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to”, “coupled to”, or “adjacent” another elementor layer, it can be directly on, connected, coupled, or adjacent theother element or layer, or intervening elements or layers may bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected to”, “directly coupled to”, or “immediatelyadjacent” another element or layer, there are no intervening elements orlayers present.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the inventive concepts belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present specification and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Hereinafter, a semiconductor device according to an embodiment of theinventive concepts will be described with reference to FIGS. 1 to 4C.

FIG. 1 is a layout view illustrating gate structures and active fins ofa semiconductor device according to an embodiment of the inventiveconcepts, FIG. 2 is a perspective view illustrating one of the gatestructures and one of the active fins of the semiconductor device ofFIG. 1 , FIG. 3 is a cross-sectional view taken along the line A-A′ ofFIG. 1 , FIG. 4A is a cross-sectional view taken along the line B-B′ ofFIG. 1 , FIG. 4B is a cross-sectional view taken along the line B1-B1′of FIG. 1 , illustrating a region A1 of FIG. 1 , and FIG. 4C is across-sectional view taken along the line B2-B2′ of FIG. 1 ,illustrating a region A2 of FIG. 1 . Note that in FIGS. 1 and 2 spacersthat are provided on sides of the gate structures are not illustrated tomore clearly show the design of the gate structures. These spacers areshown in FIGS. 3, 4B and 4C.

Referring to FIGS. 1 to 4C, the semiconductor device 1 includes activefins F1 to F4, gate structures GS1 and GS2, and a field insulation layer22. It will be appreciated that the semiconductor device may includemore gate structures and active fins.

The active fins F1 to F4 may protrude from a substrate 10 and may extendin a first direction X.

The substrate 10 may include a semiconductor material. The semiconductormaterial may include, for example, one or more selected from the groupconsisting of Si, Ge, SiGe, GaP, GaAs, SiC, SiGeC, InAs and InP.However, aspects of the inventive concepts are not limited thereto, andin other embodiments of the inventive concepts, the substrate 10 may bean insulating substrate such as, for example, a silicon on insulator(SOI) substrate. When the substrate 10 is an SOI substrate, a responsespeed of the semiconductor device 1 may be improved.

As illustrated in FIG. 1 , the active fins F1 to F4 may extend in, forexample, a first direction X, and may be spaced apart from each otherin, for example, a second direction Y.

Each of the active fins F1 to F4 may have long sides and short sides. InFIG. 1 , the long-side direction of the active fins F1 to F4 is thefirst direction X, and the short-side direction of the active fins F1 toF4 is the second direction Y, but aspects of the inventive concepts arenot limited thereto. For example, in other embodiments of the inventiveconcepts, the long-side direction of the active fins F1 to F4 may be thesecond direction Y and the short-side direction of the active fins F1 toF4 may be the first direction X.

The active fins F1 to F4 may be formed from respective portions of thesubstrate 10 and may each include an epitaxial layer that is grown fromthe substrate 10.

In some embodiments of the inventive concepts, the active fins F1 to F4may include a semiconductor material. The active fins F1 to F4 mayinclude, for example, Si or SiGe.

In some embodiments of the inventive concepts, the active fins F1 to F4may include the same material as the substrate 10. When the substrate 10includes, for example Si, the active fins F1 to F4 may include Si.

However, aspects of the inventive concepts are not limited thereto, andthe substrate 10 and the active fins F1 to F4 may include differentmaterials.

When the substrate 10 includes, for example Si, the active fins F1 to F4may include a different material from Si. In this case, the active finsF1 to F4 may be formed on the substrate 10 through, for example, anepitaxial growth process.

The field insulation layer 22 may be formed on the substrate 10 and maycover lower portions of sidewalls of the active fins F1 to F4 whileexposing top portions of the active fins F1 to F4.

As shown, the field insulation layer 22 may be adjacent the long sidesof the active fins F1 to F4.

As illustrated in FIG. 2 , line segments LS are defined where the topsurface of the field insulation layer 22 contacts each long side of theactive fins F1 to F4. Portions of each line segment LS may be covered bythe gate structures GS1 and GS2 while other portions thereof areexposed, which will be described in detail later.

In some embodiments of the inventive concepts, the field insulationlayer 22 may include, for example, one selected from the groupconsisting of an oxide layer, a nitride layer or an oxynitride layer,but aspects of the inventive concepts are not limited thereto.

The gate structures GS1 and GS2 may extend on the active fins F1 to F4in a second direction Y so as to intersect the active fins F1 to F4.

While the gate structures GS1 and GS2 are shown in FIG. 1 as extendingin the second direction Y, aspects of the inventive concepts are notlimited thereto. In embodiments, the gate structures GS1 and GS2 mayintersect the first and second fins F1 to F4 at an acute angle and/or anobtuse angle.

As illustrated, the gate structure GS1 may be spaced apart from the gatestructure GS2 in the first direction X.

The gate structure GS1 may include a gate insulation layer 112, a workfunction control layer 113 and a conductive layer 114.

As illustrated in FIG. 3 , the gate insulation layer 112 may be formedon a top surface of the active fin F2 and may protrude upwardly from thesubstrate 10 along sidewalls of a spacer 111.

The gate insulation layer 112 may have the above-described shape becausethe gate structure GS1 according to the present embodiment is formed by,for example, a gate replacement process.

In addition, as illustrated in FIG. 4A, the gate insulation layer 112may extend along a top surface of the field insulation layer 22 and sidesurfaces and a top surface of the active fin F2 in the second directionY.

The gate insulation layer 112 may include a high-k material having ahigher dielectric constant than silicon oxide. The gate insulation layer112 may include, for example, HfO₂, ZrO₂, LaO, Al₂O₃ or Ta₂O₅, butaspects of the inventive concepts are not limited thereto.

The work function control layer 113 and the conductive layer 114 mayconstitute a gate electrode. The work function control layer 113 maycontrol a work function of the gate electrode and the conductive layer114 may fill a space formed by the work function control layer 113.

In some embodiments of the inventive concepts, the work function controllayer 113 may include a first metal and the conductive layer 114 mayinclude a second metal that is different from the first metal.

The work function control layer 113 may include portions that extendupwardly along a top surface of the gate insulation layer 112 and sidesurfaces of the conductive layer 114, as illustrated in FIG. 3 . Thework function control layer 113 may have the above-described shapebecause the gate structure GS1 according to the present embodiment isformed by, for example, a gate replacement process.

In addition, as illustrated in FIG. 4A, the work function control layer113 may extend along a top portion of the field insulation layer 22 andsidewalls and a top portion of the active fin F2 in the second directionY.

The work function control layer 113 may include, for example, at leastone of TiAl, TiAlC, TiAlN, HfSi, TiN, TaN, TiC, and TaC and theconductive layer 114 may include, for example, W or Al, but aspects ofthe inventive concepts are not limited thereto. In other embodiments,the conductive layer 114 may include a non-metal material such as, forexample, Si or SiGe. The work function control layer 113 and theconductive layer 114 may be modified to have different configurations.

The spacer 111 may be formed along at least one side of the gatestructure GS1. In some embodiments of the inventive concepts, the spacer111 may be formed along both sides of the gate structure GS1.

In the illustrated embodiment, the spacer 111 has a pillar shape, butaspects of the inventive concepts are not limited thereto. In otherembodiments, the spacer 111 may be modified to have various othershapes. In the present embodiment, the spacer 111 may include, forexample, a nitride layer such as, for example, a silicon nitride layer.

However, aspects of the inventive concepts are not limited thereto, andother materials may be used to form the spacer 111. In some embodimentsof the inventive concepts, the spacer 111 may include, for example, oneof an oxide layer and an oxynitride layer.

Impurity epitaxial regions 42 may be formed on the active fins F1 to F4on opposite sides of the gate structure GS1.

In some embodiments of the inventive concepts, the impurity epitaxialregions 42 may be formed within etched regions of the active fins F1 toF4. The impurity epitasixal regions 42 may fill these respectiverecesses. The impurity epitaxial regions 42 may be formed on the activefins F1 to F4 by, for example, an epitaxial growth process.

In some embodiments of the inventive concepts, the impurity epitaxialregions 42 may be an elevated source or drain region. Top surfaces ofthe impurity epitaxial regions 42 may be higher above the substrate 10than top surfaces of the active fins F1 to F4.

The impurity epitaxial regions 42 may include a semiconductor material.In some embodiments, the impurity epitaxial regions 42 may include, forexample, Si, but aspects of the inventive concepts are not limitedthereto.

When the semiconductor device 1 includes a PMOS transistor, the impurityepitaxial regions 42 may include a compressive stress material. Forexample, the compressive stress material may include a material having alarger lattice constant than Si, e.g., SiGe. The compressive stressmaterial may improve the mobility of carriers in channel regions definedin the active fins F1 to F4 by applying compressive stress to thechannel regions.

When the semiconductor device 1 includes an NMOS transistor, theimpurity epitaxial regions 42 may include the same material as thesubstrate 10 or a tensile stress material. For example, when thesemiconductor device 1 includes Si, the impurity epitaxial regions 42may include a material having a smaller lattice constant than Si (e.g.,SiC or SiP). The tensile stress material may improve the mobility ofcarriers in channel regions defined in the active fins F1 to F4 byapplying tensile stress to the channel regions.

Although not specifically illustrated, an interlayer dielectric layermay be formed that covers the gate structure GS1 and the impurityepitaxial regions 42.

The gate structure GS2 may have substantially the same configuration asthe gate structure GS1. In particular, the gate structure GS2 mayinclude a gate insulation layer 122 that has substantially the sameconfiguration as the gate insulation layer 112 that is included in thegate structure GS1, and a work function control layer 123 and aconductive layer 124 that may have substantially the same configurationsas the work function control layer 113 and the conductive layer 114included in the gate structure GS1.

A spacer 121 may be formed on at least one sidewall of the gatestructure GS2. The spacer 121 may have substantially the sameconfiguration as the spacer 111 that is formed on at least one sidewallof the gate structure GS1.

In the present embodiment, each gate structure GS1, GS2 may include askirt S at each region where a side of the gate structure GS1, GS2intersects a long side of one of the active fins F1 to F4.

As illustrated in FIGS. 1 and 2 , each skirt S is a portion of one ofthe gate structures GS1, GS2 that extends outwardly with a curvedprofile in the first direction X to cover a portion of respective linesegments LS that are defined by the intersections of the top surface ofthe field insulation layer 22 with the respective active fins F1 to F4.

As illustrated in FIG. 2 , each skirt S comprises a lower portion of aside of the gate structure GS1, GS2 that extends outwardly in the firstdirection X more than the remainder of the side of the gate structure tocontact a lower sidewall of a respective one of the active fins F1 toF4.

For example, as illustrated in FIG. 1 , a first skirt S-1 extendsoutwardly from the left side surface of the gate structure GS1 in thefirst direction X to contact a first long side of the active fin F3 anda second skirt S-2 extends outwardly from the right side surface of thegate structure GS1 in the first direction X to also contact the firstlong side of the active fin F3.

In addition, as illustrated in FIG. 1 , a third skirt S-3 extendsoutwardly from the left side surface of the gate structure GS1 in thefirst direction X to contact a first long side of the active fin F2 anda fourth skirt S-4 extends outwardly from the right side surface of thegate structure GS1 in the first direction X to contact the first longside of the active fin F2.

In addition, as illustrated in FIG. 1 , a fifth skirt S-5 extendsoutwardly from the left side surface of the gate structure GS2 in thefirst direction X to contact the first long side of the active fin F3and a sixth skirt S-6 extends outwardly from the right side surface ofthe gate structure GS2 in the first direction X to contact the firstlong side of the active fin F3.

In addition, as illustrated in FIG. 1 , a seventh skirt S-7 extendsoutwardly from the left side surface of the gate structure GS2 in thefirst direction X to contact the first long side of the active fin F2and an eighth skirt S-8 extends outwardly from the right side surface ofthe gate structure GS2 in the first direction X to contact the firstlong side of the active fin F2. The second skirt S-2 and the fifth skirtS-5 may be spaced apart from each other so that they are not connectedto each other. Likewise, the fourth skirt S-4 and the seventh skirt S-7may be spaced apart from each other so that they are not connected toeach other.

Since the gate structure GS1 includes the above-discussed skirts S, itmay have first regions A1 and second regions A2 that have differentwidths.

In detail, a width W1 of the first region A1 of the gate structure GS1that is adjacent the active fins F1 to F4 may be larger than a width W2of the second region A2 of the gate structure GS1 that is spaced apartfrom the active fins F1 to F4 (i.e., between two adjacent ones of theactive fins F1 to F4) and may be larger than a width W3 of a thirdregion A3 of the gate structure GS1 that is on top of the active fins F1to F4. The second width W2 may be the same as the third width W3.

Likewise, since the gate structure GS2 includes the above-discussedskirts S, it may have first regions A1, second regions A2 and thirdregions A3. Each first region may have a width that is different fromwidths of the second regions A2 and the third regions A3. The secondregions A2 and the third regions A3 may have the same widths.

In detail, a width W1 of the first region A1 of the gate structure GS2that is adjacent to the active fins F1 to F4 may be larger than a widthW2 of the second region A2 of the gate structure GS2 that is spacedapart from the active fins F1 to F4 and may be larger than a width W3 ofa third region A3 of the gate structure GS2 that is on top of the activefins F1 to F4.

In addition, since the gate structure GS2 includes the above-discussedskirts S, as illustrated in FIG. 4B, the gate structure GS2 may extendunderneath a lower portion of the spacer 121 in the first region A1while not extending underneath the lower portion of the spacer 121 inthe second region A2, as illustrated in FIG. 4C.

Since the gate structure GS2 includes the above-discussed skirts S, thewidth W1 of the first region A1 of the gate structure GS2 may be largerthan the widths W2 and W3 of the respective second and third regions A2and A3 of the gate structure GS2.

When the widths of the gate structures GS1, GS2 are larger in theregions adjacent the active fins F1 to F4 (for example, the first regionA1), the driving capability of transistors can be improved, thereby, theoperating characteristics of the semiconductor device can be improved.

FIG. 5 is a layout view illustrating gate structures and active fins ofa semiconductor device 2 according to another embodiment of theinventive concepts. FIG. 6 is a cross-sectional view taken along theline C-C′ of FIG. 5 . The following description will focus ondifferences between the present embodiment and the previously-describedembodiment.

Referring to FIGS. 5 and 6 , the semiconductor device 2 includes activefins F5 and F6, a gate structure GS3, a dummy gate structure DGS1, afield insulation layer 22 and a device isolation layer 24.

The active fins F5 and F6 may protrude from a substrate 10.

As illustrated in FIGS. 5 and 6 , the active fins F5 and F6 may extendin, for example, a first direction X, and may be spaced apart from eachother in a second direction Y. Each of the active fins F5 and F6 mayhave long sides and short sides.

The field insulation layer 22 may be formed on the substrate 10 and maycover lower portions of the long sides of the active fins F5 and F6while exposing top portions of the active fins F5 and F6. As illustratedin FIGS. 5 and 6 , the field insulation layer 22 may be adjacent thelong sides of the active fins F5 and F6.

Although not specifically illustrated, line segments LS may be definedwhere the top surface of the field insulation layer 22 contacts the longsides of the active fins F5 and F6, as illustrated in FIG. 2 . Someportions of these line segments LS may be covered by the gate structureGS3 and the dummy gate structure DGS1 while other portions of the linesegments LS may be exposed.

The gate structure GS3 may extend in a second direction Y so as tointersect the active fins F5 and F6.

The gate structure GS3 may have substantially the same configuration asthe gate structure GS1 illustrated in FIG. 1 . In particular, the gateinsulation layer 142 that is included in the gate structure GS3 may havesubstantially the same configuration as the gate insulation layer 112that is included in the gate structure GS1, and a work function controllayer 143 and a conductive layer 144 that are included in the gatestructure GS3 may have substantially the same configurations as the workfunction control layer 113 and the conductive layer 114 that areincluded in the gate structure GS1.

The spacer 141 that is on at least one side of the gate structure GS3may have substantially the same configuration as the spacer 111 that isformed on at least one side of the gate structure GS1.

Impurity epitaxial regions 42 may be formed on the active fins F5 and F6at opposite sides of the gate structure GS3.

The device isolation layer 24 may extend from at least one side of theactive fins F5 and F6 (e.g., the left side of FIG. 5 ) in the seconddirection Y. That is to say, the device isolation layer 24 may extendalong short sides of the active fins F5 and F6 in the second directionY. The device isolation layer 24 and the field insulation layer 22 maymeet each other at regions where the long sides and short sides of theactive fins F5 and F6 meet each other.

The dummy gate structure DGS1 may be spaced apart from the gatestructure GS3 in the first direction X and may extend in the seconddirection Y. The dummy gate structure DGS1 may overlap the active finsF5 and F6 and the device isolation layer 24 to then extend in the seconddirection Y. That is to say, as illustrated, ends of the active fins F5and F6 may be positioned under the dummy gate structure DGS1.

The dummy gate structure DGS1 may have substantially the sameconfiguration as the gate structure GS3. In particular, a gateinsulation layer 132 that is included in the dummy gate structure DGS1may have substantially the same configuration as the gate insulationlayer 142 that is included in the gate structure GS3, and a workfunction control layer 133 and a conductive layer 134 that are includedin the dummy gate structure DGS1 may have substantially the sameconfigurations as the work function control layer 143 and the conductivelayer 144 that are included in the gate structure GS3.

A spacer 131 that is formed on at least one side of the dummy gatestructure DGS1 may have substantially the same configuration as thespacer 141 that is formed on at least one side of the gate structureGS3.

The impurity epitaxial layer 42 may be formed on the active fins F5 andF6 on one side of the dummy gate structure DGS1.

In the present embodiment, each gate structure GS3, DGS1 may include askirt S at each region where a side of the gate structure DGS1, GS3intersects a long side of one of the active fins F5, F6.

The skirts S may extend outwardly from the dummy gate structure DGS1 andthe gate structure GS3 in the first direction X to cover some portionsof respective line segments LS that are defined by the intersections ofthe top surface of the field insulation layer 22 with the active fins F5and F6 while exposing other portions of the line segments LS.

For example, as illustrated in FIG. 5 , a ninth skirt S-9 extendsoutwardly from the right side surface of the dummy gate structure DGS1in the first direction X to contact a first long side of the active finF5, a tenth skirt S-10 extends outwardly from the left side surface ofthe gate structure GS3 in the first direction X to contact the firstlong side of the active fin F5, and an eleventh skirt S-11 extendsoutwardly from the right side surface of the gate structure GS3 in thefirst direction X to contact the first long side of the active fin F5.

The ninth skirt S-9 that extends outwardly from the right side surfaceof the dummy gate structure DGS1 in the first direction X to contact thefirst long side of the active fin F5 and the tenth skirt S-10 thatextends outwardly from the left side surface of the gate structure GS3in the first direction X to contact the first long side of the activefin F5 may not be connected to each other but may be separated from eachother, as illustrated.

As illustrated, since the left side surface of the dummy gate structureDGS1 does not intersect the active fins F5 and F6, no skirt S may beformed on the left side surface of the dummy gate structure DGS1.

FIG. 7 is a layout view illustrating a gate structure and active fins ofa semiconductor device according to still another embodiment of theinventive concepts. FIG. 8 is a cross-sectional view taken along theline D-D′ of FIG. 7 . The following description will focus ondifferences between the present embodiment and the previously describedembodiments.

Referring to FIGS. 7 and 8 , the semiconductor device 3 according to thepresent embodiment is different from the semiconductor device 2 in thatit has a different dummy gate structure configuration.

In detail, while the dummy gate structure DGS1 of the semiconductordevice 2 includes the gate insulation layer 132, the work functioncontrol layer 133, and the conductive layer 134, the dummy gatestructure DGS2 of the semiconductor device 3 may only include aconductive layer including, for example, Si or poly-Si.

As illustrated in FIG. 8 , a spacer 151 may be formed on at least oneside of the dummy gate structure DGS2.

FIG. 9A is a layout view illustrating the gate structures and activefins of a semiconductor device according to still another embodiment ofthe inventive concepts. FIG. 9B is a cross-sectional view taken alongthe line E-E′ of FIG. 9A. The following description will focus ondifferences between the present embodiment and the previously describedembodiments.

Referring to FIGS. 9A and 9B, the semiconductor device 4 according tothe present embodiment is different from the semiconductor device 2according to the previous embodiment in view of a configuration of adevice isolation layer.

In detail, unlike in the semiconductor device 2 according to theprevious embodiment in which a top surface of the device isolation layer24 is positioned at substantially the same height as top surfaces of theactive fins F5 and F6, in the semiconductor device 4 according to thepresent embodiment, a top surface of the device isolation layer 26 maybe lower than the top surfaces of the active fins F5 and F6.

Accordingly, as illustrated in FIGS. 9A and 9B, a portion of the dummygate structure DGS3 may extend below the top surfaces of the active finsF5 and F6 and the other portion of the dummy gate structure DGS3 may behigher than the top surfaces of the active fins F5 and F6.

Except for the difference in view of configuration, the dummy gatestructure DGS3 may have substantially the same configuration with thedummy gate structure DGS1 of the semiconductor device 2 illustrated inFIGS. 5 and 6 .

That is to say, a gate insulation layer 162 that is included in thedummy gate structure DGS3 may have substantially the same configurationas the gate insulation layer 132 that is included in the dummy gatestructure DGS1, and a work function control layer 163 and a conductivelayer 164 that are included in the dummy gate structure DGS3 may havesubstantially the same configurations as the work function control layer133 and the conductive layer 134 that are included in the dummy gatestructure DGS1.

A spacer 161 that is formed on at least one side of the dummy gatestructure DGS3 may have substantially the same configuration as thespacer 131 that is formed on at least one side of the dummy gatestructure DGS1.

FIG. 10 is a circuit diagram illustrating a semiconductor deviceaccording to still another embodiment of the inventive concepts. FIG. 11is a layout view of the semiconductor device of FIG. 10 .

Referring to FIG. 10 , the semiconductor device may include a pair ofinverters INV1 and INV2 that are electrically connected in parallelbetween a power supply node VCC and a ground node VSS, and a first passtransistor PS1 and a second pass transistor PS2 that are connected tothe respective output nodes of the inverters INV1 and INV2. The firstpass transistor PS1 and the second pass transistor PS2 may be connectedto a bit line BL and a complementary bit line BLb, respectively. Gatesof the first pass transistor PS1 and the second pass transistor PS2 maybe connected to a word line WL.

The first inverter INV1 includes a first pull-up transistor PU1 and afirst pull-down transistor PD1 that are electrically connected in seriesto each other, and the second inverter INV2 includes a second pull-uptransistor PU2 and a second pull-down transistor PD2 that areelectrically connected in series to each other. The first pull-uptransistor PU1 and the second pull-up transistor PU2 may be PFETtransistors, and the first pull-down transistor PD1 and the secondpull-down transistor PD2 may be NFET transistors.

In addition, in order to constitute a latch circuit, an input node ofthe first inverter INV1 is connected to an output node of the secondinverter INV2 and an input node of the second inverter INV2 is connectedto an output node of the first inverter INV1.

Referring to FIGS. 10 and 11 , a first active fin 210, a second activefin 220, a third active fin 230 and a fourth active fin 240, which arespaced apart from one another, may extend lengthwise in one direction(for example, in an up-down direction of FIG. 11 ). Here, the secondactive fin 220 and the third active fin 230 may be shorter in lengththan the first active fin 210 and the fourth active fin 240.

In addition, a first gate electrode 251, a second gate electrode 252, athird gate electrode 253, and a fourth gate electrode 254 are formed toextend lengthwise in the other direction (for example, in a left-rightdirection of FIG. 11 ). Each of the first through fourth gate electrodes251-254 may intersect one or more of the first active fin 210 throughthe fourth active fin 240.

In detail, the first gate electrode 251 completely intersects the firstactive fin 210 and the second active fin 220 while partially overlappinga terminal of the third active fin 230. The third gate electrode 253completely intersects the fourth active fin 240 and the third active fin230 while partially overlapping a terminal of the second active fin 220.The second gate electrode 252 and the fourth gate electrode 254 areformed to intersect the first active fin 210 and the fourth active fin240, respectively.

As illustrated, the first pull-up transistor PU1 is defined in thevicinity of an intersection of the first gate electrode 251 and thesecond active fin 220, the first pull-down transistor PD1 is defined inthe vicinity of an intersection of the first gate electrode 251 and thefirst active fin 210, and the first pass transistor PS1 is defined inthe vicinity of an intersection of the second gate electrode 252 and thefirst active fin 210. The second pull-up transistor PU2 is defined inthe vicinity of an intersection of the third gate electrode 253 and thethird active fin 230, the second pull-down transistor PD2 is defined inthe vicinity of an intersection of the third gate electrode 253 and thefourth active fin 240, and the second pass transistor PS2 is defined inthe vicinity of an intersection of the fourth gate electrode 254 and thefourth active fin 240.

Although not specifically illustrated, sources and drains may be formedat opposite sides of the respective intersections of the first to fourthgate electrodes 251-254 and the first to fourth active fins 210, 220,230 and 240, and a plurality of contacts 250 may be formed.

Further, a first shared contact 261 may connect the second active fin220, the third gate electrode 253, and a wiring 271 with one another. Asecond shared contact 262 may connect the third active fin 230, thefirst gate electrode 251 and a wiring 272 with one another.

At least one of the semiconductor devices according to some embodimentsof the inventive concepts can be employed as the illustrated layout ofthe SRAM.

FIG. 12 is a block diagram of a System on Chip (SoC) system includingsemiconductor devices according to embodiments of the inventiveconcepts.

Referring to FIG. 12 , the SoC system 1000 may include an applicationprocessor 1001 and a DRAM 1060.

The application processor 1001 may include a central processing unit1010, a multimedia system 1020, a bus 1030, a memory system 1040, and aperipheral circuit 1050.

The central processing unit 1010 may perform arithmetic operationsnecessary for operating the SoC system 1000. In some embodiments of theinventive concepts, the central processing unit 1010 may be configuredin a multi-core environment including a plurality of cores.

The multimedia system 1020 may be used in performing a variety ofmultimedia functions in the SoC system 1000. The multimedia system 1020may include a 3D engine module, a video codec, a display system, acamera system, and a post-processor.

The bus 1030 may be used to perform data communication among the centralprocessing unit 1010, the multimedia system 1020, the memory system1040, and the peripheral circuit 1050. In some embodiments of theinventive concepts, the bus 1030 may have a multi-layered structure.Examples of the bus 1030 may include a multi-layer advancedhigh-performance bus (AHB), or a multi-layer advanced eXtensibleinterface (AXI), but aspects of the inventive concepts are not limitedthereto.

The memory system 1040 may provide environments necessary for high-speedoperation by connecting the AP 1001 to an external memory (for example,the DRAM 1060). In some embodiments of the inventive concepts, thememory system 1040 may include a separate controller (for example, aDRAM controller) for controlling the external memory (for example, theDRAM 1060).

The peripheral circuit 1050 may provide environments necessary forsmoothly connecting the SoC system 1000 to an external device (forexample, a main board). Accordingly, the peripheral circuit 1050 mayinclude various kinds of interfaces enabling the external deviceconnected to the SoC system 1000 to be compatibly used.

The DRAM 1060 may function as a working memory of the AP 1001. In someembodiments of the inventive concepts, as illustrated, the DRAM 1060 maybe disposed outside the AP 1001. In detail, the DRAM 1060 may bepackaged with the AP 1001 in the form of a package on package (PoP).

At least one component of the SoC system 1000 may employ one of theaforementioned semiconductor devices according to embodiments of theinventive concepts.

FIG. 13 is a block diagram of an electronic system includingsemiconductor devices according to embodiments of the inventiveconcepts.

Referring to FIG. 13 , the electronic system 1100 may include acontroller 1110, an input/output device (I/O) 1120, a memory device1130, an interface 1140 and a bus 1150. The controller 1110, the I/O1120, the memory device 1130, and/or the interface 1140 may be connectedto each other through the bus 1150. The bus 1150 corresponds to a paththrough which data moves.

The controller 1110 may include at least one of a microprocessor, adigital signal processor, a microcontroller, and logic elements capableof functions similar to those of these elements. The I/O 1120 mayinclude a key pad, a key board, a display device, and so on. The memorydevice 1130 may store data and/or commands. The interface 1140 mayperform functions of transmitting data to a communication network orreceiving data from the communication network. The interface 1140 may bewired or wireless. For example, the interface 1140 may include anantenna or a wired/wireless transceiver, and so on.

Although not illustrated, the electronic system 1100 may further includehigh-speed DRAM and/or SRAM as the working memory for improving theoperation of the controller 1110. Semiconductor devices according toembodiments of the inventive concepts may be employed as the workingmemory.

In addition, semiconductor devices according to embodiments of theinventive concepts may be provided in the memory device 1130 or may beprovided in some components of the controller 1110 or the I/O 1120.

The electronic system 1100 may be applied to a personal digitalassistant (PDA), a portable computer, a web tablet, a wireless phone, amobile phone, a digital music player, a memory card, or any type ofelectronic device capable of transmitting and/or receiving informationin a wireless environment.

FIGS. 14 to 16 illustrate exemplary semiconductor systems to whichsemiconductor devices according to some embodiments of the inventiveconcepts can be applied.

FIG. 14 illustrates an example in which a semiconductor device accordingto an embodiment of the inventive concepts is applied to a tablet PC(1200), FIG. 15 illustrates an example in which a semiconductor deviceaccording to an embodiment of the inventive concepts is applied to anotebook computer (1300), and FIG. 16 illustrates an example in which asemiconductor device according to an embodiment of the inventiveconcepts is applied to a smart phone (1400). At least one of thesemiconductor devices according to some embodiments of the inventiveconcepts can be employed to a tablet PC 1200, a notebook computer 1300,a smart phone 1400, and the like.

In addition, semiconductor devices according to some embodiments of theinventive concepts may also be applied to other integrated circuitdevices not illustrated herein.

That is to say, in the above-described embodiments, only the tablet PC1200, the notebook computer 1300 and the smart phone 1400 have beenexemplified as including semiconductor devices according to embodimentsof the inventive concepts, but aspects of the inventive concepts are notlimited thereto.

In some embodiments of the inventive concepts, the semiconductor devicemay be implemented as a computer, an ultra mobile personal computer(UMPC), a work station, a net-book, a personal digital assistant (PDA),a portable computer, a web tablet, a wireless phone, a mobile phone, ane-book, a portable multimedia player (PMP), a potable game console, anavigation device, a black box, a digital camera, a 3-dimensional (3D)television, a digital audio recorder, a digital audio player, a digitalpicture recorder, a digital picture player, a digital video recorder, adigital video player, or the like.

FIGS. 17 to 20 are diagrams illustrating a method for fabricatingsemiconductor devices according to some embodiments of the inventiveconcepts.

Referring to FIG. 17 , an active fin F2 is formed to protrude upwardlyfrom a substrate 10. The active fin F2 may extend in a first directionXl.

In detail, in some embodiments of the inventive concepts, the active finF2 may be formed by etching the substrate 10. In other embodiments, theactive fin F2 may be formed by forming an epitaxial layer including asemiconductor material on the substrate 10 and patterning the epitaxiallayer.

Next, a field insulation layer 22 covering a bottom portion of theactive fin F2 is formed on the substrate 10. Then, a conductive layer 72is formed on the field insulation layer 22 and the active fin F2. Here,the conductive layer 72 may include, for example, polycrystallinesilicon (poly-Si).

Next, referring to FIG. 18 , the conductive layer 72 is patterned suchthat it intersects the active fin F2. The conductive layer 72 may bepatterned to form skirts S at regions where the conductive layer 72 andthe active fin F2 are adjacent each other.

Referring to FIG. 19 , spacers 74 may be formed at opposite sides of theconductive layer 72. The spacers 74 may include, for example, aninsulating material such as, for example, a silicon nitride layer or asilicon oxynitride layer.

Referring to FIG. 20 , the conductive layer (72 of FIG. 19 ) is removed.As a result of removing the conductive layer (72 of FIG. 19 ), skirtholes SH may be formed under the spacers 74.

Thereafter, a gate structure GS1, including a gate insulation layer(e.g., 112 of FIG. 3 ), a work function control layer (e.g., 113 of FIG.3 ), and a conductive layer (e.g., 114 of FIG. 3 ), is formed betweenthe spacers 74, and the gate structures GS1 to GS3 of the semiconductordevices 1 to 4 may be formed in substantially the same manner.

Further, a device isolation layer (for example, 24 of FIG. 6, 26 of FIG.9B) may be formed at one side of the active fin F2, the dummy gatestructures DGS1 and DGS3 of the semiconductor devices 2 and 4 may beformed in substantially the same manner.

Finally, if the conductive layer 72 illustrated in FIG. 19 is allowed toremain without being removed, the dummy gate structure DGS2 of thesemiconductor device 3 may also be formed.

While the inventive concepts have been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the inventive concepts as defined by the following claims. It istherefore desired that the present embodiments be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than the foregoing description to indicatethe scope of the inventive concepts.

What is claimed is:
 1. A semiconductor device comprising: a first activefin protruding from a substrate and extending in a first direction; asecond active fin protruding from the substrate and extending in thefirst direction, wherein the second active fin is spaced apart from thefirst active fin in a second direction that intersects the firstdirection; and a first gate structure extending in the second direction,the first gate structure includes a gate insulation layer, a workfunction control layer on the gate insulation layer and a conductivelayer on the work function control layer, wherein the first gatestructure includes a first skirt where a first side of the first gatestructure extends outwardly in the first direction to contact a sidesurface of the first active fin, a second skirt where a second side ofthe first gate structure, which is opposite the first side of the firstgate structure, extends outwardly in the first direction to contact theside surface of the first active fin, a third skirt where the first sideof the first gate structure extends outwardly in the first direction tocontact a side surface of the second active fin, and a fourth skirtwhere the second side of the first gate structure extends outwardly inthe first direction to contact the side surface of the second activefin, wherein each of outer surfaces of the first skirt, the secondskirt, the third skirt, and the fourth skirt has a first concave profileat a lower half portion of the first gate structure in a vertical plane,wherein each of the outer surfaces of the first skirt, the second skirt,the third skirt, and the fourth skirt has a second concave profile in ahorizontal plane, wherein an entirety of the first skirt having thefirst concave profile in the vertical plane continuously decreases inwidth, in the first direction, with increasing height above a surface ofthe substrate, wherein the entirety of the first skirt having the secondconcave profile in the horizontal plane continuously increases in width,in the first direction, with decreasing distance to the side surface ofthe first active fin, wherein the first skirt includes the gateinsulation layer and the work function control layer, an outer surfaceof the gate insulation layer of the first skirt has the first concaveprofile in the vertical plane, and an outer surface of the work functioncontrol layer of the first skirt has a third concave profile in thevertical plane, wherein an entirety of the work function control layerof the first skirt having the third concave profile in the verticalplane continuously decreases in width, in the first direction, withincreasing height above the surface of the substrate, and wherein thesecond concave profile in the horizontal plane converges with the firstconcave profile in the vertical plane.
 2. The semiconductor device ofclaim 1, wherein a width of the first gate structure in the firstdirection decreases from the side surface of the first active fin to aregion between the first active fin and the second active fin.
 3. Thesemiconductor device of claim 1, further comprising a dummy gatestructure extending in the second direction, to cross the first activefin, the first active fin having an end in the first direction under thedummy gate structure, wherein the dummy gate structure is spaced apartfrom the first gate structure in the first direction, and wherein thedummy gate structure includes a fifth skirt where a first side of thedummy gate structure facing the first side of the first gate structureextends outwardly in the first direction to contact the side surface ofthe first active fin and a sixth skirt where the first side of the dummygate structure extends outwardly in the first direction to contact theside surface of the second active fin.
 4. The semiconductor device ofclaim 3, wherein an outer surface of the fifth skirt has a fourthconcave profile at a lower half portion of the dummy gate structure inthe vertical plane, wherein the outer surface of the fifth skirt has afifth concave profile in the horizontal plane, and wherein an entiretyof the fifth skirt having the fourth concave profile in the verticalplane continuously decreases in width, in the first direction, withincreasing height above the surface of the substrate.
 5. Thesemiconductor device of claim 3, wherein a second side of the dummy gatestructure, which is opposite the first side of the dummy gate structure,is a planar side surface that does not include any skirt.
 6. Thesemiconductor device of claim 3, further comprising a device isolationlayer that extends in the second direction and is contact with the endof the first active fin, wherein the dummy gate structure is on thefirst active fin and the device isolation layer.
 7. The semiconductordevice of claim 1, further comprising a second gate structure extendingin the second direction, wherein the second gate structure is spacedapart from the first gate structure, and wherein the second gatestructure includes a seventh skirt where a first side of the second gatestructure facing the second side of the first gate structure extendsoutwardly in the first direction to contact a side surface of the firstactive fin and an eighth skirt where the first side of the second gatestructure extends outwardly in the first direction to contact the sidesurface of the second active fin.
 8. The semiconductor device of claim7, wherein each of outer surfaces of the seventh and eighth skirts hasthe first concave profile at a lower half portion of the second gatestructure in the vertical plane, wherein each of the outer surfaces ofthe seventh and eighth skirts has the second concave profile in thehorizontal plane, and wherein an entirety of the seventh skirt havingthe first concave profile in the vertical plane continuously decreasesin width, in the first direction, with increasing height above thesurface of the substrate.
 9. The semiconductor device of claim 7,wherein a distance between the first gate structure and the second gatestructure in the first direction increases from the side surface of thefirst active fin to a region between the first active fin and the secondactive fin.
 10. A semiconductor device comprising: a first active finprotruding from a substrate and extending in a first direction; a secondactive fin protruding from the substrate and extending in the firstdirection, wherein the second active fin is spaced apart from the firstactive fin in a second direction that intersects the first direction;and a first gate structure extending in the second direction, the firstgate structure includes a gate insulation layer, a work function controllayer on the gate insulation layer and a conductive layer on the workfunction control layer, wherein the first gate structure includes afirst skirt where a first side of the first gate structure extendsoutwardly in the first direction to contact a side surface of the firstactive fin, wherein an outer surface of the first skirt has a firstconcave profile at a lower half portion of the first gate structure in avertical plane, wherein the outer surface of the first skirt has asecond concave profile in a horizontal plane, wherein an entirety of thefirst skirt having the first concave profile in the vertical planecontinuously decreases in width, in the first direction, with increasingheight above a surface of the substrate, wherein the first skirtincludes the gate insulation layer and the work function control layer,an outer surface of the gate insulation layer of the first skirt has thefirst concave profile in the vertical plane, and an outer surface of thework function control layer of the first skirt has a third concaveprofile in the vertical plane, wherein an entirety of the work functioncontrol layer of the first skirt having the third concave profile in thevertical plane continuously decreases in width, in the first direction,with increasing height above the surface of the substrate, and whereinthe second concave profile in the horizontal plane converges with thefirst concave profile in the vertical plane.
 11. The semiconductordevice of claim 10, wherein the entirety of the first skirt having thesecond concave profile in the horizontal plane continuously increases inwidth, in the first direction, with decreasing distance to the sidesurface of the first active fin.
 12. The semiconductor device of claim10, wherein the first gate structure further includes a second skirtwhere a second side of the first gate structure, which is opposite thefirst side of the first gate structure, extends outwardly in the firstdirection to contact the side surface of the first active fin, a thirdskirt where the first side of the first gate structure extends outwardlyin the first direction to contact a side surface of the second activefin, and a fourth skirt where the second side of the first gatestructure extends outwardly in the first direction to contact the sidesurface of the second active fin.
 13. The semiconductor device of claim10, further comprising a dummy gate structure extending in the seconddirection, to cross the first active fin, the first active fin having anend in the first direction under the dummy gate structure, wherein thedummy gate structure is spaced apart from the first gate structure inthe first direction, and wherein the dummy gate structure includes afifth skirt where a first side of the dummy gate structure facing thefirst side of the first gate structure extends outwardly in the firstdirection to contact the side surface of the first active fin, and asixth skirt where the first side of the dummy gate structure extendsoutwardly in the first direction to contact the side surface of thesecond active fin.
 14. The semiconductor device of claim 13, wherein anouter surface of the fifth skirt has a fourth concave profile at a lowerhalf portion of the dummy gate structure in the vertical plane, whereinthe outer surface of the fifth skirt has a fifth concave profile in thehorizontal plane, and wherein an entirety of the fifth skirt having thefourth concave profile in the vertical plane continuously decreases inwidth, in the first direction, with increasing height above the surfaceof the substrate.
 15. The semiconductor device of claim 10, furthercomprising a second gate structure extending in the second direction,wherein the second gate structure is spaced apart from the first gatestructure, wherein the second gate structure includes a seventh skirtwhere a first side of the second gate structure facing a second side ofthe first gate structure extends outwardly in the first direction tocontact a side surface of the first active fin and an eighth skirt wherethe first side of the second gate structure extends outwardly in thefirst direction to contact the side surface of the second active fin.16. A semiconductor device comprising: a first active fin protrudingfrom a substrate and extending in a first direction; a second active finprotruding from the substrate and extending in the first direction,wherein the second active fin is spaced apart from the first active finin a second direction that intersects the first direction; and a firstgate structure extending in the second direction, wherein the first gatestructure includes a first skirt where a first side of the first gatestructure extends outwardly in the first direction to contact a sidesurface of the first active fin, a second skirt where a second side ofthe first gate structure, which is opposite the first side of the firstgate structure, extends outwardly in the first direction to contact theside surface of the first active fin, a third skirt where the first sideof the first gate structure extends outwardly in the first direction tocontact a side surface of the second active fin, and a fourth skirtwhere the second side of the first gate structure extends outwardly inthe first direction to contact the side surface of the second activefin, wherein each of outer surfaces of the first skirt, the secondskirt, the third skirt, and the fourth skirt has a first concave profileat a lower half portion of the first gate structure in a vertical plane,wherein each of the outer surfaces of the first skirt, the second skirt,the third skirt, and the fourth skirt has a second concave profile in ahorizontal plane, wherein an entirety of the first skirt having thefirst concave profile in the vertical plane continuously decreases inwidth, in the first direction, with increasing height above a surface ofthe substrate, wherein the entirety of the first skirt having the secondconcave profile in the horizontal plane continuously increases in width,in the first direction, with decreasing distance to the side surface ofthe first active fin, wherein the second concave profile in thehorizontal plane converges with the first concave profile in thevertical plane, and wherein a first width of the first gate structure inthe first direction decreases from the side surface of the first activefin to a region between the first active fin and the second active fin.17. The semiconductor device of claim 16, wherein the first gatestructure includes a gate insulation layer, a work function controllayer on the gate insulation layer and a conductive layer on the workfunction control layer.
 18. The semiconductor device of claim 16,further comprising a second gate structure extending in the seconddirection, wherein the second gate structure is spaced apart from thefirst gate structure, wherein the second gate structure includes a fifthskirt where a first side of the second gate structure facing the secondside of the first gate structure extends outwardly in the firstdirection to contact a side surface of the first active fin and a sixthskirt where the first side of the second gate structure extendsoutwardly in the first direction to contact the side surface of thesecond active fin.
 19. The semiconductor device of claim 18, wherein adistance between the first gate structure and the second gate structurein the first direction increases from the side surface of the firstactive fin to a region between the first active fin and the secondactive fin.